1. Field of the Invention
The present invention relates to a method of producing quick-cooking rice mainly from long-grain and medium-grain rice as raw material rice (brown rice, partially-milled rice), and the quick-cooking rice produced by the method.
2. Description of Related Art
Conventionally, there is quick-cooking rice that can be returned to the cooked state within a short period of time by adding water or boiled water. Examples of quick-cooking rice include parboiled rice and instant rice. Parboiled rice is widely consumed in America and Europe as well as Asian countries, such as India and Pakistan. Parboiled rice is produced by steam-boiling (alpharizing) raw material unhulled rice, and the rice is then dried, hulled, and milled. When prepared for consumption, it is boiled in water for approximately 10 minutes. Since parboiled rice is produced by steam-boiling raw material unhulled rice as it is in the producing process, the chaff odor and others seep into the endosperm, thereby providing a branny flavor.
In recent years, consumer preferences with respect to the taste of parboiled rice have diversified, and the number of consumers who dislike the branny flavor of parboiled rice has increased. To get around this problem, parboiled rice without a smell of bran has been developed. Examples of a method of producing parboiled rice include those disclosed in Japanese Unexamined Patent Application Publication Nos. 2008-220221 and 2009-27950. In the producing method disclosed in these gazettes, brown rice is used as a raw material. After being partially milled, the brown rice is subjected to a moisture adding process by spraying or humidification and air draft, a moisture conditioning process, and then a normal-pressure steam-boiling and a pressurized steam-boiling process for alpharization of the rice grains. Then, after a cooling process, a finish milling process, and a drying process, parboiled rice (product) is produced. According to this producing method, since the raw material brown rice is steam-boiled, parboiled rice without a branny flavor can be obtained.
However, in this method of producing parboiled rice, when raw material rice is subjected to a moisture adding process, cracks may occur on the surface of rice grains if the moisture addition speed is increased. Therefore, the moisture addition speed is made slow (sluggish) to prevent the occurrence of cracks associated with addition of moisture (moisture addition speed: 0.5%/h to 0.8%/h). For this reason, in the moisture adding process, a long time is disadvantageously required for addition of moisture.
Instant rice has a particularly short cooking time among quick-cooking rice, for example, approximately five minutes to ten minutes for cooking. An example of a method of producing instance rice is disclosed in, for example, Japanese Patent No. 4099036. In this producing method, partially-milled rice as a raw material is sequentially subject to primary soaking, and then primary alpharization (normal-pressure steam-boiling), preliminary drying, finish milling (high-moisture milling), secondary soaking, secondary alpharization (normal-pressure steam-boiling), single granulation, and finish drying.
However, in the method of producing parboiled rice described above, when raw material rice is subjected to a moisture adding process, cracks may occur on the surface of rice grains if the moisture addition speed is increased. Therefore, the moisture addition speed is made slow (sluggish) to prevent the occurrence of cracks associated with addition of moisture (moisture addition speed: 0.5%/h to 0.8%/h). For this reason, in the moisture adding process, a long time is disadvantageously required for addition of moisture. Also in the method of producing instant rice described above, as with the case of parboiled rice, raw material rice in a raw state is soaked into water in a soak tank in the moisture adding process. Unless a long time is taken for this moisture adding process, cracks may occur on the surface of rice grains. Therefore, the moisture adding process requires a long time.
Moreover, in the method of producing instant rice described above, raw material rice grains are soaked into warm water (at approximately 80 degrees Celsius) in a soak tank in the processes of primary and secondary soaking, and therefore a large amount of warm water is used. For this reason, a drainage facility for processing warm water after soaking is required, thereby disadvantageously increasing cost of a production facility.
In both of the method of producing parboiled rice and the method of producing instant rice, when the rice grains of the raw material rice with cracks occurring in the moisture adding process are alpharized in a subsequent alpharizing process or the like, the cracks on the surface of the rice grains may be in a torn state to let nutrients inside the rice grains elute. Also, the shape of the rice grains may be destroyed to degrade the outer appearance of the product.
In view of the problems described above, a technical object of the present invention is to provide a method of producing quick-cooking rice capable of preventing cracks in rice grains in a moisture adding process and also reducing time required for the moisture adding process.
Another problem to be solved is to provide a method of producing quick-cooking rice without requiring a drainage facility.